1. Field of the Invention
The present invention generally relates to information storage apparatuses, and, more particularly, to an information storage apparatus that performs optimum data read/write operations regardless of the recording density of the recording medium. The present invention also relates to a method of controlling such an information storage apparatus.
2. Description of the Related Art
FIG. 1 is a block diagram of a conventional magnetic disk unit 20 that comprises: a hard disk controller (HDC) 4 connected to a host computer 12 via a small computer system interface (SCSI); a data buffer 5 and a random access memory (RAM) 3 connected to the HDC 4; a flash ROM 2 connected to the RAM 3, a micro-controller unit (MCU) 1 connected to the flash ROM 2; a drive interface 6 connected to the MCU 1 and the HDC 4; a servo driver 8 and a digital signal processor (DSP) 7 both connected to the driver interface 6; a read channel 10 connected to the drive interface 8 and the HDC 4; a servo demodulator 9 connected to the drive interface 6 and the read channel 10; and a disk enclosure 11, which contains a magnetic disk, connected to the servo driver 8 and the read channel 10.
FIGS. 2A and 2B show track formats of servo information each recorded on a data surfaces of a magnetic disk partitioned by means of a conventional embedded servo technique.
More specifically, FIG. 2A shows the format of a track on a magnetic disk partitioned by index information 21: every three data sectors 23 are separated by servo frames 22. Servo information is written to the magnetic disk unit 20 by a read/write head, and is used for positioning the head. The partitioning of the data sectors 23 and the data density controlled magnetic disk may be varied by changing the data write frequency, for instance. The recording density is 12 sectors per track.
FIG. 2B shows the format of another track partitioned by index information 21: every four data sectors 23 are separated by the servo frames 22, so that the recording density of the track format is 16 sectors per track, while the recording density of the track format of FIG. 2A is 12 sectors per track.
Where the recording densities of the disks differ, two types of firmware must be installed, so that two different magnetic disk units must be produced.
From the financial and developmental viewpoint, magnetic disk units having the same drive engine must be customized in order to provide for differences in their peripheral functions. More specifically, if there is a demand for magnetic disk units having different functions, it is more troublesome to produce different magnetic disk units than to customize the magnetic disk units having the same drive engine. Accordingly, the firmware of each magnetic disk unit is independently produced in accordance with each corresponding customizing request, while the hardware is the same for all the magnetic disk units. A firmware design change is more easily and quickly accomplished than a hardware design change. Nevertheless, it is preferable to maximize the number of common elements in firmware.
More specifically, some clients prefer their customized magnetic disk units to have the maximum recording capacity, while others prefer a reduced recording capacity in their customized magnetic disk units. When a client requests a recording capacity beyond the standard range, the track density would be increased to its maximum, and the system usage area, such as log storage area and defective sector area, would be reduced.
Magnetic disk units with different types of firmware are accordingly produced with different recording densities. Unfortunately, read/write operations can be performed only when magnetic disks have a fixed recording density. With conventional magnetic disk units, read/write operations performed on magnetic disks having different recording densities are prone to errors that are often difficult to detect, and the magnetic disk units might overrun without providing an error indication.
A general object of the present invention is to provide information storage apparatuses and information storage apparatus control methods in which the above disadvantages are eliminated.
A more specific object of the present invention is to provide an information storage apparatus that adjusts to different recording densities, and a method of controlling such an information storage apparatus.
The above objects of the present invention are achieved by an information storage apparatus that performs read/write operations on a recording medium, comprising:
a storage unit that stores a plurality of control parameters corresponding to the different recording densities that the recording medium;
a control unit that sets one of the plurality of control parameters stored in the storage unit at the time of activation, determines whether the set control parameter is suitable for properly reading out data from the recording medium, and selects the control parameter determined to be suitable for controlling the recording medium among the plurality of control parameters.
In this information storage apparatus, a suitable control parameter is selected in accordance with the recording density of the recording medium, so that a data read/write operation can be properly performed regardless of the recording density of the recording medium.
The above objects of the present invention are also achieved by an information storage apparatus which performs a data read/write operation on a recording medium, comprising:
a formatting unit which formats the recording medium at a recording density corresponding to a set command inputted.
In this information storage apparatus, the recording density of the recording medium can be easily changed.
The above objects of the present invention are also achieved by a method of controlling an information storage apparatus which performs a data read/write operation on a recording medium, the method comprising the steps of:
setting one control parameter among a plurality of control parameters corresponding to recording densities that the recording medium can have;
determining whether the set control parameter is suitable for properly reading data from the recording medium; and
selecting the control parameter determined to be suitable for properly reading the data from the recording medium among the plurality of control parameters.
The above objects of the present invention are also achieved by a method of controlling an information storage apparatus which performs a data read/write operation on a recording medium, the method comprising the steps of:
formatting the recording medium at a recording density corresponding to a set command inputted.
The above and other objects and features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.